(1) Field of the Invention
The present invention relates to a beam scanning type information readout device, particularly to a beam scanning type information readout device which can read omnidirectionally the information for a product expressed in bar-code-format by means of a beam scanner which can be carried in the hand.
(2) Description of the Prior Art
The existing bar-code-information readout devices can be roughly classified into the light-pen type and stationary scanner type. The former results in a disadvantage of reduced information readout efficiency in that the scanning speed fluctuates and the point floats because an operator moves the pen on the bar-code-symbol. Moreover, the latter also results in disadvantages in that the structure is complicated and the physical dimensions are large due to the stationary nature, thus, a more costly device, and, additionally, an operator has less freedom in operation due to the stationary nature. On the other hand, an information readout device, which can be carried easily and has improved information readout efficiency by focusing on the above-mentioned points, has become known. This is generally called a hand scanner. This device by itself is lightweight, capable of processing the bar-code-information for the products, and has a high information reading ratio through high speed laser beam scanning. Details of such a device are described, for example, in Japanese Laid Open Patent Publication No. 52-148146 and 53-66330.
However, the hand scanner device, described above, uses a mirror which generates vibrations in the laser beam scanning system and, therefore, results in disadvantages in that the structure is complicated, mechanical vibration and noise are considerably high, energy efficiency is bad, and high speed scanning is restricted because the size of the mirror is limited based on inertia. In addition, such a device has the disadvantage that there is no possibility of omnidirectional reading between the readout information area (hereinafter called the bar-code-symbol for simplification) and the device. This is because only one scanning line is used and scanning is made only in a single direction and an operator always has to be concerned about direction matching.